Anomalous regularity and scaling limit by rough transport noise for stochastic 2D fluid models on the torus

We consider the stochastic 2D Euler and mSQG equations on the torus, with L² initial data and driven by rough Kraichnan transport noise, for which we construct weak solutions enjoying anomalous regularity and dissipation properties. Moreover, we show that weak solutions in this regularity class are pathwise unique, thus establishing probabilistically strong well-posedness. We further obtain the scaling limit from these equations to the deterministic Navier--Stokes/mSQG equations, with respect to positive Sobolev norms. The proofs rest on the analysis of energy spectrum of the vorticity and on a uniform weighted discrete Poincaré inequality on the lattice, the latter being crucial for making the positive norms accessible.